In addition to an HDD (Hard Disk Drive), an SSD (Solid State Drive) is used as an external storage device for information processing devices such as a personal computer. The SSD includes a NAND flash memory as a nonvolatile semiconductor memory.
For example, in the case that the SSD is used in the same environment as the HDD, if data is rewritten frequently, the SSD will age (wear out) faster. Therefore, when an insufficient test (screening) is performed before product shipment, a failure rate increases after the product shipment.
In order to improve reliability of the SSD, it is conceivable that the data is repeatedly rewritten in the SSD during a screening process before the product shipment. However, the screening increases a screening time and a screening cost.